How to Prevent Firefox From Using Too Much Memory

Stop your browser from consuming too many system resources

How to Prevent Firefox from Using Too Much Memory

Mozilla’s Firefox browser does an excellent job providing stable, fast performance with a minimal memory footprint. But there may be scenarios where Firefox is using too much memory and requires user intervention to increase both browser and system-based performance. Here's how to prevent Firefox from using too much memory, using tactics such as starting in safe mode, removing extensions, and more.

Firefox Usage Best Practices

First, start with the simple solutions. Close tabs you simply don’t need, restart Firefox and update your graphics drivers. Consider installing extensions that block unwanted content and using the built-in Task Manager (use the About command about:performance by typing it into the address bar) to view and close tabs consuming the most memory.

How to Update Firefox

Updating Firefox is always a good idea. Not only are you installing security patches, but Mozilla tweaks the backend for better performance. If a bug causing memory leaks exists, you’ll see a downgrade in overall system performance as the CPU and operating system deal with multiple tasks. Updating Firefox could eliminate possible memory-related issues.

  1. Click the hamburger icon in the top-right corner to open the Firefox menu.

  2. Click Options on the drop-down menu.

    Select Options in Firefox
  3. The Preferences page opens with the General category loaded by default. Scroll down to Firefox Updates.

  4. Click Check for updates.

    Check for updates in Firefox

    Here you can choose to manage update settings such as enabling automatic updates or checking for updates and installing them manually. Firefox uses background services and updates search engines by default.

  5. Restart Firefox if needed.

Check for Resource-Hogging Extensions and Themes

If you’re not using extensions and/or themes, bypass this section altogether. However, if one or both are in place, you may need to see if they’re causing performance issues. That requires loading Firefox in Safe Mode.

  1. Type about:support in the address bar and press the Enter key.

  2. Click Restart with Add-ons Disabled under Try Safe Mode.

    Restart Firefox with add-ons disabled
  3. Click Start in Safe mode when Firefox restarts.

  4. Use Firefox as normal while checking your memory and CPU percentage. 

If memory and/or CPU usage is still high, then extensions and themes are not the issue. If the numbers remain low, disable themes and extensions.

How to Disable Firefox Extensions

The idea here is to disable all extensions to see if the memory issue clears. If it does, then re-enable each extension one at a time to determine the offending, memory-gulping addition.

  1. Click the hamburger icon in the top right corner. This opens the Firefox menu.

  2. Select Add-ons in the drop-down menu.

    Select Add-ons in Firefox
  3. Select Extensions in the menu on the left.

  4. Click on the three-dot icon next to an extension.

  5. Select Disable on the drop-down menu.

    Disable add-ons in Firefox
  6. Repeat for each extension.

  7. Click the hamburger Firefox menu button in the top right corner.

  8. Select Exit to close the browser.

    Exit Firefox

Once you determine the offending extension, click the three-button icon as seen in Step 3 and select Options to edit its settings. If that doesn’t work, check to see if there’s an option to update the extension. If not, click the Remove option to uninstall the offending extension from Firefox.

How to Disable Firefox Themes

If an extension is not your memory-hogging issue, a downloaded theme could be the problem. Simply revert to the default theme to see if system performance increases.

  1. Click the hamburger icon in the top right corner. This opens the Firefox menu.

  2. Select Add-ons in the drop-down menu.

    Select Add-ons in Firefox
  3. Select Themes in the menu on the left.

  4. Click the three-dot button next to Default listed under Disabled.

  5. Select Enable on the pop-up menu.

    Enable the default theme in Firefox
  6. Click the hamburger Firefox menu button in the top right corner.

  7. Select Exit to close the browser.

    Exit Firefox

How to Toggle Hardware Acceleration

This is a two-edged sword. On one hand, hardware acceleration means Firefox dumps page rendering and other tasks on your PC’s hardware for faster performance rather than rely solely on slower software-based computing. However, hardware acceleration may cause issues, depending on your configuration.

  1. Click the hamburger icon in the top right corner. This opens the Firefox menu.

  2. Select Options in the drop-down menu.

    Select Options in Firefox
  3. The Preferences page opens with the General category loaded by default. Scroll down to Performance.

  4. By default, Firefox enables the Use recommended performance settings option. Click to uncheck.

  5. Uncheck the Use hardware acceleration when available feature.

    Tweak the performance in Firefox

Here you can also change the content process limit. A higher number means better performance when running multiple tabs at the cost of additional memory. Eight is the default setting, but if you’re experiencing memory issues, try lowering the process number.

Use the Built-In Memory Tool

Firefox provides a built-in tool to show memory reports and save logs. Here you have access to three buttons that can clear junk in the memory and minimize memory usage.

  1. Type about:memory in the address bar and press the Enter key.

  2. Locate the Free memory panel and click Minimize memory usage.

    Manually free memory in Firefox
  3. Optionally, you can click the GC (garbage collection) and CC (cycle collection) buttons.

How to Install a Firefox Extension

While this step appears to be a complete 180 given the previous instructions to disable extensions, this specific offering could help ease your memory troubles. This guide suggests Auto Tab Discard, which suspends inactive tabs after a specific time. These tabs remain open, but the content isn’t actively rendered, showing a grey dot over the site’s logo on the tab.

  1. Head to the Auto Tab Discard listing on Mozilla’s Firefox Add-ons page.

  2. Click Add to Firefox.

    Add the Auto Tab Discard extension
  3. Click Add in the in-browser pop-up window that appears.

    Add the Auto Tab Discard extension
  4. Click Okay, Got It to confirm the add-on management instructions.

    Suspend tabs with Auto Tab Discard

You’ll now see a power button icon located next to the Firebox menu button. Click Auto Tab Discard to access quick commands to close the current tab, close other tabs in the current window, and more.

The Options section provides settings for discarding options, conditions, and exceptions. By default, this extension will discard inactive tabs after 600 seconds when the number of inactive tabs exceeds six.

Reduce Firefox Session History

One possible memory hog is your Firefox session history. Click and hold on the browser’s back and forward buttons and you’ll see a history of the sites you visited. The maximum per-session history limit is 50, meaning Firefox stores 50 webpage addresses in memory. Since you’re unlikely to rewind and fast-forward through this lengthy list, reduce that number to reduce Firefox’s memory footprint.

  1. Type about:config in the address bar and press the Enter key.

  2. Type browser.sessionhistory.max_entries in the search field and press the Enter key.

  3. Double-click on the current value (50).

  4. Enter a lower number in the pop-up window’s text field.

    Reduce the session history in Firefox
  5. Click the OK button.

  6. Click the hamburger button in Firefox to access its menu.

  7. Select Exit.

    Exit Firefox

Delete the content-prefs.sqlite File

The file storing individual website data may be corrupt. Delete this file and Firefox will create another once it restarts.

  1. Type about:support in the address bar and press the Enter key.

  2. Click Open Folder, shown next to Profile Folder, listed under Application Basics.

    Locate your Profile folder in Firefox
  3. Right-click on the content-prefs.sqlite file listed within that folder and select Delete.

    Delete the content-prefs-sqlite file
  4. Click the hamburger button in Firefox to access its menu.

  5. Select Exit.

    Exit Firefox

When All Else Fails, Refresh Firefox

Finally, refresh Firefox to its factory defaults if nothing else works.

  1. Type about:support in the address bar and press the Enter key.

  2. Click Refresh Firefox.

    Click the Refresh Firefox button
  3. Click Refresh Firefox in the pop-up window that appears to confirm.

    Refresh Firefox
  4. Click Finish when Firefox restarts.